Green Tea Medical Benefits
Hear What Scientists Say

What do scientists say about green tea medical benefits? Which tea is better? How about extract supplements?

Green tea is booming. According to the Tea Association, 2006 was the 15th
consecutive year that consumers bought more tea than ever. Retail supermarket
sales neared 2 billion dollars.

Are the consumers right? Many people are
already taking green tea medical benefits for granted. What do the scientists
say? How much is proven? Which products are more credible?

There are many
questions. But first, lets try to understand the allure of green
tea.

Science Catching
Up

Green tea medical benefits have been quoted in ancient Chinese
texts for as long as people have been drinking it.

Pharmacist Chen Zang
famously remarked:

Every medicine is the only medicine for a specific
disease, but tea is the medicine for all causes.

But it is only recently
that scientists have started to pay attention.

“Scientific investigations
of tea compounds began less than 30 years ago, and most have been conducted in
just the past 5 years,” says Hasan Mukhtar and his co-authors in the July issue
of the journal Life Sciences.

Top Healthy Beverage

"As a nutrition scientist, I consider tea as a healthy choice for three
reasons:

It meets hydration needs, it has no calories and It is really rich in
phytonutrients (plant-based substances) that we know provide some human health
benefits."

Dr. Jeffrey Blumberg, Director of the Antioxidants Research Laboratory at
Tufts University in Boston, Mass, continues to say:

"Tea has more of the catechins (a group of phytochemicals that act as
antioxidants) than any food I am aware of. It is far and away the biggest,
richest best source of those phytonutrients, and It is a pleasant, aromatic and
flavorful beverage."

Medicine For All Causes

"The most fascinating thing is, to my knowledge, there is no other
natural product known that has such diversified effects," says Hasan Mukhtar,
vice chair of dermatology at the University of Wisconsin-Madison.

Think of an ailment. Chances are some research suggests tea might protect
against it.

Most green tea medical benefits studies are either population
or laboratory based.

A population study may show that cancer is less
common in countries where people drink a lot of green tea. A laboratory study is
conducted in petri dishes or animals.

None of which provide conclusive
evidence. The most conclusive evidence would come from human trials, but not many of
them have been conducted.

It is still in the early days. After all, the
scientific evidence snowballs have just begun to roll in the last 5
years.

“Drinking tea can't hurt, and, most likely, it can help,” says
Mukhtar and other tea researchers. They point to the tea’s 5,000-year track
record of safety.

Here are some of the more talked-about of green tea
medical benefits, coming from the mouths of scientists themselves.

Green Tea Medical Benefits #1:
Protect From Heart
Disease

“Tea polyphenols, as compounds with antioxidant activity,
may protect against heart disease and a variety of cancers,” Mukhtar says.

Public health nutritionist Dr. Carrie Ruxton, and colleagues at Kings
College London, looked at published studies on the health effects of tea
consumption.

They found clear evidence that drinking 3 to 4 cups of tea a
day can cut the chances of having a heart attack.

"Drinking tea is actually better for you than drinking water. Water is
essentially replacing fluid. Tea replaces fluids and contains antioxidants so
it's got two things going for it," says Dr. Ruxton.

Claire Williamson of the British Nutrition Foundation said: "Studies in the
laboratory have shown potential health benefits."

The evidence in humans
is not as strong and more studies need to be done. But there are definite
potential health benefits from the polyphenols in terms of reducing the risk of
diseases such as heart disease and cancers.

"In terms of fluid intake, we
recommend 1.5-2 litres per day and that can include tea. Tea is not dehydrating.
It is a healthy drink."

Green Tea Medical Benefits #2:
Prevent
Cancer

Mukhtar’s own research has shown that green and black tea, when
substituted for drinking water, inhibits the growth of human prostate cancer
cells implanted in mice.

He reported that topical application or
ingestion of green tea polyphenols protects against skin cancer in
mice.

“Green tea compounds positively affect genes involved in cancer
susceptibility and DNA repair, although not everyone will respond equally well,”
says Iman Hakim, a professor at the Arizona Cancer Center at the University of
Arizona.

“An ongoing clinical trial of former and current smokers with
chronic obstructive pulmonary disease has found a significant improvement in
levels of HDL, or good, cholesterol in volunteers given tea as opposed to a
placebo drink.”

"If tea proves to be good, it might be good to switch the
kids to tea," says Hakim, who notes that tea contains less caffeine than
coffee.

Green Tea Medical Benefits
#3:
Feel
Good

John Foxe, professor of neuroscience, biology and psychology at City College
of the City University of New York, has conducted clinical trials of theanine,
an amino acid in tea that, unlike polyphenols, is small enough to cross the
blood/brain barrier.

"Probably quite a lot of people have heard tea has cardiovascular effects,"
says Foxe, whose work was financed by Unilever, maker of Lipton tea.

"But that's
not why people drink tea. They drink it because it makes them feel
good."

Green Tea Medical Benefits
#4:
Better
Concentration

“People who drank a solution containing about as much theanine as 10
cups of tea were able to focus better on tasks than those who drank a placebo
solution,” says Foxe at an international symposium on tea and human health in
Washington.

“As little as 100 milligrams of theanine enabled people to
focus better on complicated tasks, but only when consumed with 60 milligrams of
caffeine — a combination found in roughly 4 cups of green tea,” says Foxe more
recently.

"There was a profound synergistic effect," he says. "My take
is, we're all self-medicating with this."

Which Tea?

“Green tea seems to have more
health cachet than black tea, perhaps because it has been the focus of more
research. Although not as well-studied as green tea, black tea probably is at
least as beneficial,” says Mukhtar.

He drinks 2 cups of black tea and 2
of green a day.

Green Tea
Extract?

Just because drinking tea might be good for you doesn't mean adding tea
extract to cereal and other foods or to dietary supplements is
beneficial.

"A lot of that is gimmick," Mukhtar says of products that
tout tea extract as an ingredient.

"There are not very many studies on tea supplements, yet the
few we have suggest they are mimicking some of the cardio and cancer benefits
established in tea studies," says Dr. Jeffrey Blumberg.

"You are going to get some of the same benefits from tea
extracts, but they are not the same thing."

"I have a slight bias as a nutrition scientist. Mother
Nature put a lot of different beneficial chemicals and compounds in tea so why
not take advantage of all of them?"

"By definition, supplements are 80 to 90 percent concentrated polyphenol extracts, primarily EGCG, a powerful antioxidant, but as
far as I know, theanine amino acid is not in extracts, and theanine is what
helps you to focus your attention on a task or relax."

Overdose Danger

A paper published in April about green tea medical benefits suggests one
danger of such products with high doses of green tea extracts.

"There are
quite a few case reports on liver damage due to taking supplements that contain
tea extracts," says biochemist Chung Yang, a Rutgers University cancer
researcher who co-wrote the paper in the journal Chemical Research Toxicology.

“Liver function returned to normal when those affected stopped taking
the supplements.

In addition, studies in rodents and dogs suggest that high
doses of tea catechins can damage the kidneys and intestine as well as the
liver.

”Tea drinkers shouldn't worry, though", Yang emphasizes: "It's very
clear, there are no published reports concerning toxicity due to tea
consumption."